Neuropathology associated with stillbirth

A role for immunohistochemical stains in perinatal brain autopsies

Identification of central nervous system injury is a critical part of perinatal autopsies; however, injury is not always easily identifiable due to autolysis and immaturity of the developing brain. Here, the role of immunohistochemical stains in the identification of perinatal brain injury was investigated. Blinded semiquantitative scoring of injury was performed on sections of frontal lobe from 76 cases (51 liveborn and 25 stillborn) using H&E, GFAP, Iba-1, and β-APP stains. Digital image analysis was used to quantify GFAP and Iba-1 staining. Commonly observed pathologies included diffuse white matter gliosis (DWMG) and white matter necrosis (WMN). DWMG scores were very similar on H&E and GFAP stains for liveborn subjects. For stillborn subjects, DWMG scores were significantly higher on GFAP stain than H&E. β-APP was needed for identification of WMN in 71.4% of stillborn subjects compared to 15.4% of liveborn subjects. Diffuse staining for Iba-1 within cortex and white matter was positively correlated with subject age. Staining quantification on digital image analysis was highly correlated to semiquantitative scoring. Overall, GFAP and β-APP stains were most helpful in identifying white matter injury not seen on H&E in stillborn subjects. Immunostains may therefore be warranted as an integral part of stillborn brain autopsies.

Silver nanoparticles in the fetal brain: new perspectives in understanding the pathogenesis of unexplained stillbirths

We report, for the first time, the surprising presence of toxic nanoparticles, especially silver, in the brain of a fetus, who died unexpectedly at the end of a regular pregnancy. After an accurate autopsy, including the examination of the fetal annexes, an in-depth anatomopathological study of the nervous system and a search by scanning electron microscopy of nanoparticles in the brain, we highlighted the sequence of events that may have led to this fetal death, triggered primarily by the transition of nanosized xenobiotics from the mother to the fetal bloodstream. From this report emerges the importance of considering the search of nanosubstances in the brain during routine investigations following unexpected and unexplained fetal and infant deaths.

Mechanisms of death in structurally normal stillbirths

Objectives To investigate mechanisms of in utero death in normally formed fetuses by measuring amniotic fluid (AF) biomarkers for hypoxia (erythropoietin [EPO]), myocardial damage (cardiac troponin I [cTnI]) and brain injury (glial fibrillary acidic protein [GFAP]), correlated with risk factors for fetal death and placental histopathology. Methods This retrospective, observational cohort study included intrauterine deaths with transabdominal amniocentesis prior to induction of labor. Women with a normal pregnancy and an indicated amniocentesis at term were randomly selected as controls. AF was assayed for EPO, cTnI and GFAP using commercial immunoassays. Placental histopathology was reviewed, and CD15-immunohistochemistry was used. Analyte concentrations >90th centile for controls were considered "raised". Raised AF EPO, AF cTnI and AF GFAP concentrations were considered evidence of hypoxia, myocardial and brain injury, respectively. Results There were 60 cases and 60 controls. Hypoxia was present in 88% (53/60), myocardial damage in 70% (42/60) and brain injury in 45% (27/60) of fetal deaths. Hypoxic fetuses had evidence of myocardial injury, brain injury or both in 77% (41/53), 49% (26/53) and 13% (7/53) of cases, respectively. Histopathological evidence for placental dysfunction was found in 74% (43/58) of these cases. Conclusion Hypoxia, secondary to placental dysfunction, was found to be the mechanism of death in the majority of fetal deaths among structurally normal fetuses. Ninety-one percent of hypoxic fetal deaths sustained brain, myocardial or both brain and myocardial injuries in utero. Hypoxic myocardial injury was an attributable mechanism of death in 70% of the cases. Non-hypoxic cases may be caused by cardiac arrhythmia secondary to a cardiac conduction defect.

Acute thymic involution in unexplained third trimester stillbirth: frequency, grade, and correlation with neuropathologic injury

Many 3rd-trimester stillbirths are unexplained, including the time course of the illness. Histologic acute thymic involution (ATI), when graded, correlates with duration of acute illness (grade 0, <12 hours; grade 4, >72 hours). Histologic brain injury is also common in stillbirth. We investigated ATI in unexplained stillbirth and correlated it with neuropathologic injury by identifying 58 autopsies of unexplained, 3rd-trimester stillborns (preterm, n  =  24; term, n  =  34) that included brain examination and graded ATI from 0 (resting state) to 4 (pronounced lymphodepletion). Gray matter injury (GMI) and white matter injury (WMI) were classified as older, recent, or absent, and ATI was correlated with GMI, WMI, thymic weight, and clinical data. Nine cases (16%) had ATI grade 0-1; 19 (33%), grade 2; 24 (41%), grade 3; and 6 (10%), grade 4. Older GMI and WMI were present in 39 (67%) and 10 (17%) stillborns, respectively. Higher ATI grade correlated significantly with older GMI (P < 0.001) and WMI (P  =  0.014). The ATI grade was higher in the small-for-gestational stillborns compared with the appropriate- or large-for-gestational stillborns (P  =  0.017) but did not correlate significantly with gestational age or other clinical or demographic factors evaluated. The ATI grades 2-4 were found in 84% of the stillborns, consistent with onset of acute illness between 24 and >72 hours before demise. Higher ATI grade correlated significantly with older brain injury, suggesting similar time of onset and shared underlying pathophysiologic events, the specific nature of which remains unclear.

The neuropathology of stillbirth - correlation with apolipoprotein genotype in a Scottish population based study

BACKGROUND

The neuropathology of stillbirths has been widely studied but rarely on a population basis. Whether foetal apolipoprotein E (APOE) genotype exerts any influence has been little investigated, despite well known effects in adult brains.

AIMS

To establish the neuropathology of a population cohort of stillbirths and compare with the APOE genotype.

STUDY DESIGN AND SUBJECTS

The brains of 191 stillbirths (≥24weeks of gestation) were recruited from a Scottish population cohort and grouped by clinical history. APOE genotype was available for 97%.

RESULTS AND CONCLUSIONS

One or more neuropathological features, most appearing relatively recent, were found in 54% of 157 antepartum singletons, 44% of 9 abruption-associated stillbirths, 85% of 13 in multiple pregnancies but in only 19% of 12 intrapartum stillbirths. White matter injury (WMI) occurred in 36% of preterm and 21% mature stillbirths. Fresh petechial haemorrhages were common in all groups (29%) but germinal matrix haemorrhage (GMH) (7%) and periventricular leucomalacia (1%) were confined to preterm. GMH was significantly associated with WMI (p=0.003). Placental inflammation was common in intrapartum stillbirths (50%), compared with antepartum (15%), multiple pregnancy (23%) and abruption (0%). β-Amyloid precursor protein (βAPP) positive axons (36% stillbirths overall) correlated closely with WMI (p<0.0001), justifying future routine inclusion in foetal neuropathological investigation. This study highlights the paucity of brain damage in intrapartum stillbirths. While APOE2 was significantly overrepresented in stillbirths, there was no correlation between APOE genotype and neuropathological findings. We conclude that APOE does not influence neuropathological outcomes in stillbirths.

Antenatal brain injury in third trimester neonates with severe congenital anomalies: an autopsy study

OBJECTIVE

With advances in therapy, more neonates with severe congenital anomalies are surviving, albeit some with neurologic disorders, possibly related to antenatal low brain blood flow. This autopsy series reports antenatal brain injury in neonates expiring due to severe anomalies, and provides correlation with umbilical cord blood gas and acid-base analysis.

METHODS

We identified autopsies of third trimester neonates expiring shortly following delivery due to severe anomalies or malformations. Brain injury classified as "older" included periventricular leukomalacia, gliosis and karyorrhectic neurons, and "recent" included red neurons and reactive glial changes.

RESULTS

We identified 22 cases (nine term, 13 preterm). 16 (73%) had brain injury, including 11 with older injury. Cord arterial blood was analyzed in 17, and six had pH <7 or base deficit >12 mmol/L. Four out of 5 (80%) neonates with neuronal necrosis compared to two out of 12 (17%) without had a pH <7 or base deficit >12 mmol/L (p = 0.03). Five out of nine (56%) neonates with white matter injury compared to one out of 8 (13%) without had pH <7 or base deficit >12 mmol/L (p = NS).

CONCLUSIONS

Antenatal brain injury is frequent in neonates with severe congenital anomalies. Severely abnormal cord blood analysis results correlate significantly with neuronal necrosis and show a trend toward white matter injury; however, the absence of these abnormal results does not preclude the presence of brain injury.

Third trimester fetal demise occurring at time of delivery: correlation of autopsy findings and placental pathology with emphasis on antenatal central nervous system injury

OBJECTIVE

Third trimester fetal deaths occurring in the hospital at the time of delivery are unusual. We report an autopsy series of such cases with emphasis on neuropathological injury and other lesions predating delivery.

METHODS

We identified autopsies performed on third trimester fetuses documented to be alive shortly before delivery, but that expired during, or very close to, time of delivery, and we correlate autopsy and placental findings. Fetuses with major congenital anomalies were excluded.

RESULTS

Ten cases were identified (6 term, 4 preterm). All were delivered by cesarean section and had attempted resuscitation. Established or recent brain injury was identified in 9 of 10 cases, including 3 with established neuronal damage and 1 with periventricular leukomalacia. Additional autopsy findings included thymic involution in eight (five mild; three severe), myocardial infarcts in two; intrathoracic petechiae in five, and ascites or pleural or pericardial effusions in six. Severe thymic involution and myocardial infarcts correlated with established brain injury. Placental lesions adaptive to decreased oxygenation (increased nucleated red blood cells or villous hypervascularity) were seen in five cases and correlated with established brain injury. Acute chorioamnionitis with funisitis was present in one, and chronic inflammatory placental lesions were present in six.

CONCLUSIONS

These findings indicate brain injury predated the time period immediately before delivery in 9 of 10 fetuses, and in the fetuses with established brain injury the onset of acute illness was possibly >72 h before delivery.

A rat pup model of cerebral palsy induced by prenatal inflammation and hypoxia

Animal models of cerebral palsy established by simple infection or the hypoxia/ischemia method cannot effectively simulate the brain injury of a premature infant. Healthy 17-day-pregnant Wistar rats were intraperitoneally injected with lipopolysaccharide then subjected to hypoxia. The pups were used for this study at 4 weeks of age. Simultaneously, a hypoxia/ischemia group and a control group were used for comparison. The results of the footprint test, the balance beam test, the water maze test, neuroelectrophysiological examination and neuropathological examination demonstrated that, at 4 weeks after birth, footprint repeat space became larger between the forelimbs and hindlimbs of the rats, the latency period on the balance beam and in the Morris water maze was longer, place navigation and ability were poorer, and the stimulus intensity that induced the maximal wave amplitude of the compound muscle action potential was greater in the lipopolysaccharide/hypoxia and hypoxia/ischemia groups than in the control group. We observed irregular cells around the periventricular area, periventricular leukomalacia and breakage of the nuclear membrane in the lipopolysaccharide/hypoxia and hypoxia/ischemia groups. These results indicate that we successfully established a Wistar rat pup model of cerebral palsy by intraperitoneal injection of lipopolysaccharide and hypoxia.

Fetal central nervous system injury in third trimester stillbirth: a clinicopathologic study of 63 cases

We report the neuropathologic findings and clinicopathologic associations in 63 3rd trimester singleton stillborn fetuses. All were ≥ 28 weeks estimated gestational age (EGA) with complete autopsies, including placental examination. Fetuses with chromosomal abnormalities, major congenital anomalies, and intrapartum demise were excluded. The cases were divided into those with abruption (n  =  12) and those with unexplained fetal demise (n  =  51). The latter group was then subdivided by gestational age with 3 subgroups (preterm 28 to < 32 weeks EGA (n  =  16), preterm 32 to <37 weeks EGA (n  =  13), and term 37-41 weeks EGA (n  =  22). Each group was further subdivided as appropriate-for-gestational age/large-for-gestational age (AGA/LGA) or small-for-gestational age (SGA). Placental lesions were also evaluated and correlated with brain lesions. Established or recent injury involving gray or white matter was seen in 88% of the fetuses with unexplained demise versus 42% with abruption (P  =  0.001). The most common form of brain injury was established gray matter damage, seen in 65% of the fetuses with unexplained demise versus 25% with abruption (P  =  0.021), the most common pattern being established pontosubicular neuronal necrosis plus established neuronal necrosis in other sites. There was no significant difference in the frequency of brain injury between the SGA fetuses and AGA/LGA fetuses or between the unexplained stillbirth preterm and term subgroups, and there was no unequivocal correlation between placental lesions and brain lesions. Brain injury, most frequently established gray matter damage, is seen in the majority of stillborn infants with unexplained demise, indicating that the brain injury predates the period immediately before death.

The Stillbirth Collaborative Research Network neuropathologic examination protocol

We describe the neuropathologic procedure utilized in the Stillbirth Collaborative Research Network (SCRN), focusing on the examination of central nervous system (CNS) in stillbirth (SB). The SCRN was organized to perform a case-control study to determine the scope and causes of SB. Pathologists at all the participating centers agreed on and used the same standardized neuropathologic techniques. Standardized sections were taken and detailed data were collected. Fresh brain tissue was saved for investigative purposes. A total of 663 women with SB were enrolled into the case-control study: 620 delivered a single stillborn, 42 delivered twins, and 1 delivered triplets. Of the 560 (84.5%) who consented to postmortem examination, 465 (70.1%) also gave consent to the examination of the CNS. In the 440 stillborn infants in whom CNS examination was possible, 248 (56.4%) of the brains were intact, 72 were fragmented (16.4%), and 120 (27.3%) were liquefied. In summary, this is the largest prospective study dedicated to investigate the causes of SB and collect essential information and biological samples in the United States. A protocol for neuropathologic examination was instituted, and a brain tissue repository was created to provide samples and related data for future investigations.

Unexplained stillbirth versus SIDS: common congenital diseases of the autonomic nervous system--pathology and nosology

OBJECTIVE

To contribute to a more balanced assessment of the morphological substrates underlying unexplained perinatal death and SIDS.

METHODS

In-depth histological, immunohistochemical and genetic examinations were performed on the autonomic nervous and cardiac conduction systems in 95 unexpected perinatal deaths, 140 SIDS and 78 controls (44 infants and 34 perinatal death victims).

RESULTS

The study revealed the localization and the nature of a variety of specific congenital abnormalities of the autonomic nervous system, central and peripheral, and of the cardiac conduction system that represent the morphological substrates of the pathophysiological mechanism of sudden fetal death and SIDS.

CONCLUSIONS

The observation of similar anomalies of the autonomic nervous and the cardiac conduction systems in both unexplained perinatal deaths and SIDS indicates their common congenital nature. Therefore, the definitions of these deaths, currently nosographically distinct, should be unified.

Stillbirth classification--developing an international consensus for research: executive summary of a National Institute of Child Health and Human Development workshop

Stillbirth is a major obstetric complication, with 3.2 million stillbirths worldwide and 26,000 stillbirths in the United States every year. The Eunice Kennedy Shriver National Institute of Child Health and Human Development held a workshop from October 22-24, 2007, to review the pathophysiology of conditions underlying stillbirth to define causes of death. The optimal classification system would identify the pathophysiologic entity initiating the chain of events that irreversibly led to death. Because the integrity of the classification is based on available pathologic, clinical, and diagnostic data, experts emphasized that a complete stillbirth workup should be performed. Experts developed evidence-based characteristics of maternal, fetal, and placental conditions to attribute a condition as a cause of stillbirth. These conditions include infection, maternal medical conditions, antiphospholipid syndrome, heritable thrombophilias, red cell alloimmunization, platelet alloimmunization, congenital malformations, chromosomal abnormalities including confined placental mosaicism, fetomaternal hemorrhage, placental and umbilical cord abnormalities including vasa previa and placental abruption, complications of multifetal gestation, and uterine complications. In all cases, owing to lack of sufficient knowledge about disease states and normal development, there will be a degree of uncertainty regarding whether a specific condition was indeed the cause of death.

Fetal magnetic resonance imaging of acquired and developmental brain anomalies

During the last decade, increasing interest in magnetic resonance imaging has emerged for the evaluation of fetal abnormalities detected on ultrasound. The advent of single-shot rapid acquisition sequences has greatly facilitated our ability to obtain detailed imaging information of the fetal brain. To date, fetal magnetic resonance imaging has shown to have an important role in the investigation of cerebral abnormalities suspected by sonography, and in the detection of subtle brain anomalies associated with high-risk pregnancies. Magnetic resonance imaging has proved to be a useful adjunct to sonography during the prenatal period of development, especially for the detection of acquired disorders.

Stillborn or liveborn? Comparing umbilical cord immunohistochemical expression of vitality markers (tryptase, alpha(1)-antichymotrypsin and CD68) by quantitative analysis and confocal laser scanning microscopy

The distinction between stillborn and liveborn infants and the demonstration of a separate existence of fetuses are central issues in the daily practice of perinatologists and pathologists. The current knowledge about the chronology of responses of the tissue following the occurrence of a vital reaction, as well as the existence of numerous studies that aimed at identifying markers of vitality of cutaneous lesions, induced us to investigate the umbilical cord for the presence or absence of vitality indexes. We investigated 45 samples of umbilical cords obtained during post-mortem examinations of stillborns, as well as samples of umbilical cords taken from newborns after normal labor. On these samples, we performed a complete immunohistochemical study. Our results showed that some of the parameters investigated, such as tryptase for the mast cell, CD68, and alpha-1-antichymotrypsin, showed a statistically significant (p<0.0001) different expression in the two groups under study (stillborn and liveborn). Owing to the strong different expression of these markers in the samples of the umbilical cords from liveborns, compared to those from stillborns, one might regard them as reliable parameters, to which the pathologist may resort whenever he is dealing with the distinction between stillborns and liveborns.

Unexpected perinatal loss versus Sids-a common neuropathologic entity

Objective: To evaluate the involvement of alterations of the central autonomic nervous system, particularly of the brainstem and cerebellum, in a wide set of victims of sudden and unexplained perinatal and infant death.

Material and Methods: The study population consisted of 63 stillbirths, 28 neonatal deaths and 140 suspected SIDS. The victims were subjected to in-depth anatomopathological examination following appropriate guidelines. The protocol included, in particular, the histological evaluation on serial sections of the cardiorespiratory autonomic nervous system.

Results: A diagnosis of “unexplained death” was established for 217 of the 231 victims (59 stillbirths, 28 newborns and 130 SIDS). In a very high percentage of these deaths (84%) we observed one or more anomalies of the nuclei and/or structures of the brainstem and cerebellum related to vital functions.

Conclusion: Unexpected perinatal loss should not be regarded as a separate entity from SIDS, given the common neuropathological substrates.

Neuronal cell death in the arcuate nucleus of the medulla oblongata in stillbirth

The hypothesis that unexplained stillbirth arises in a similar manner as the sudden infant death syndrome (SIDS) is based in part on shared neuropathologic features between the two entities, including hypoxic-ischemic lesions such as white matter and brainstem gliosis, as well as aplasia or hypoplasia of the arcuate nucleus on the ventral surface of the medulla. The arcuate nucleus is the putative homologue of the respiratory chemosensory region at the ventral medullary surface in animals that is involved in central chemosensitivity. To determine arcuate nucleus pathology in stillbirth, and its co-occurrence with evidence of hypoxia-ischemia, we reviewed brain specimens from the archives of our hospitals from 22 consecutive stillbirths from 22 to 41 gestational weeks. Explained causes of death (n=17) included nuchal cord, acute chorioamnionitis, placental abruption, and fetal glomerulosclerosis; 5 cases were unexplained. In 12 brains, we observed nuclear karyorrhexis and/or pyknosis with cytoplasmic hypereosinophilia in neurons in the arcuate nucleus in both explained (n=8) and unexplained (n=4) cases (54.5% of total cases). Three additional cases had arcuate aplasia (n=1) or hypoplasia (n=2) (13.6% of total cases); one of the latter cases also had neuronal necrosis in the hypoplastic arcuate. The degree of gliosis in the region of the arcuate nucleus was variable across all cases, without statistically significant differences between groups with and without arcuate nucleus necrosis. Other lesions in association with (n=14) and without (n=8) arcuate nucleus abnormalities were diffuse cerebral white matter gliosis, periventricular leukomalacia (PVL), and neuronal necrosis in the hippocampus, basal ganglia, thalamus, basis pontis, and brainstem tegmentum. In 16/20 (80.0%) cases (with or without histologic necrosis of the arcuate), immunostaining with caspase-3 demonstrated positive neurons. Our findings suggest that neuronal pathology in the arcuate nucleus may be both developmental (13.6%) and acquired (54.5%). The association of neuronal necrosis and apoptosis in the arcuate nucleus with systemic entities involving fetal ischemia, and with other brain lesions consistent with ischemia, e.g., cerebral white matter gliosis, suggests that ischemia plays a role in the arcuate nucleus damage as well. Thus, the underpopulation of arcuate neurons detected postnatally in some SIDS infants may be secondary to an acquired insult in mid- or late gestation, and in other cases, a primary developmental lesion in early gestation, or both. The role of arcuate nucleus pathology in the pathogenesis of fetal demise remains to be determined.

Anesthetic-mediated protection/preconditioning during cerebral ischemia

Cerebral ischemia is a multi-faceted neurodegenerative pathology that causes cellular injury to neurons within the central nervous system. In light of the underlying mechanisms being elucidated, clinical trials to find possible neuroprotectants to date have failed, thus highlighting the need for new putative targets to offer protection. Recent evidence has clearly shown that anesthetics can confer significant protection and or induce a preconditioning effect against cerebral ischemia-induced injury. This review will focus on the putative protection/preconditioning that is afforded by anesthetics, their possible interaction with GABA(A) and glutamate receptors and two-pore potassium channels. In addition, the interaction with inflammatory, apoptotic and underlying molecular (particularly immediately early genes and inducible nitric oxide synthase etc) pathways, the activation of K(ATP) channels and the ability to provide lasting protection will also be addressed.

Periventricular leukomalacia: overview and recent findings

Periventricular leukomalacia (PVL), the main substrate for cerebral palsy, is characterized by diffuse injury of deep cerebral white matter, accompanied in its most severe form by focal necrosis. The classic neuropathology of PVL has given rise to several hypotheses about the pathogenesis, largely relating to hypoxia-ischemia and reperfusion in the sick premature infant. These include free radical injury, cytokine toxicity (especially given the epidemiologic association of PVL with maternofetal infection), and excitotoxicity. Among the recent findings directly in human postmortem tissue is that immunocytochemical markers of lipid peroxidation (hydroxy-nonenal and malondialdehyde) and protein nitration (nitrotyrosine) are significantly increased in PVL. Premyelinating oligodendrocytes, which predominate in periventricular regions during the window of vulnerability to PVL (24 to 34 postconceptional weeks), are the targets of this free radical injury, and suffer cell death. Susceptibility can be attributed, at least in part, to a relative deficiency of superoxide dismutases in the preterm white matter, including premyelinating oligodendrocytes. Several cytokines, including interferon-gamma (known to be directly toxic to immature oligodendroglia in vitro), as well as tumor necrosis factor-alpha and interleukins 2 and 6, have been demonstrated in PVL. Microglia, which express toll-like receptors to bacterial products such as lipopolysaccharide, are increased in PVL white matter and may contribute to the injury. Preliminary work suggests a role for glutamate receptors and glutamate transporters in PVL, as has been seen in experimental animals. These findings pave the way for eventual therapeutic or preventive strategies for PVL.

Are maternal hypertension and small-for-gestational age risk factors for severe intraventricular hemorrhage and cystic periventricular leukomalacia? Results of the EPIPAGE cohort study

OBJECTIVE

The purpose of this study was to examine the relationships between different causes of preterm delivery (eg, maternal hypertension, small-for-gestational age [SGA], other) and cerebral damage (eg, cystic periventricular leukomalacia [c-PVL], grade III intraventricular hemorrhage [IVH], and intra-parenchymal hemorrhage [IPH]).

STUDY DESIGN

This study included 1902 very preterm singletons who were transferred to neonatal intensive care units in 9 French regions. We used logistic regression models to compare the risk of cerebral injury associated with maternal hypertension, SGA, and all other causes of preterm delivery.

RESULTS

We found that the risk of c-PVL and grade III IVH was higher in infants born after preterm premature rupture of membranes (PPROM) with short latency or idiopathic preterm labor than in infants born to hypertensive mothers. We show that SGA and antepartum maternal hemorrhage significantly increase the risk of IPH.

CONCLUSION

Our results show that infants born to hypertensive mothers have a lower risk of cerebral injuries than infants born following idiopathic preterm labor and PPROM because they are less exposed to prenatal infection.

Sudden infant death syndrome, infection and inflammatory responses

Sudden infant death syndrome (SIDS) is sudden unexpected death in infancy for which there is no explanation after review of the history, a death scene investigation and a thorough autopsy. The use of common diagnostic criteria is a prerequisite for discussing the importance of infection, inflammatory responses and trigger mechanism in SIDS. Several observations of immune stimulation in the periphery and of interleukin-6 elevation in the cerebrospinal fluid of SIDS victims explain how infections can play a role in precipitating these deaths. Finally, these findings and important risk factors for SIDS are integrated in the concept of a vicious circle for understanding the death mechanism. The vicious circle is a concept to elucidate the interactions between unfavourable factors, including deficient auto-resuscitation, and how this could result in death.

Preliminary study on the cytoarchitecture of the human parabrachial/Kölliker-fuse complex, with reference to sudden infant death syndrome and sudden intrauterine unexplained death

The parabrachial/Kölliker-Fuse complex has been defined, in different animal species, to lie in the dorsolateral part of the pontine tegmentum and to be subdivided into three well-defined regions: the medial parabrachial nucleus, the lateral parabrachial nucleus, and the Kölliker-Fuse nucleus. Experimental studies have shown that the parabrachial/Kölliker-Fuse complex is involved in a variety of functional activities and above all plays an important role in respiratory modulation. In human brainstem, the cytoarchitecture and physiology of this complex have not yet been fully characterized. The aim of the present study was to examine fetal and infant human brainstems in order to define the precise morphology of the three nuclei of the parabrachial/Kölliker-Fuse complex, and to determine whether this nervous center shows morphologic alterations in sudden infant death syndrome (SIDS) and in sudden intrauterine unexplained death (SIUD). In serial sections of 31 brainstems of subjects aged from 32 gestational wk to 10 months of life, we studied, by morphologic and morphometric analyses, the cytoarchitecture and the extension of the three nuclei of the parabrachial/Kölliker-Fuse complex. All the morphometric parameters were very similar in SIUD and SIDS cases to those of the respective control group, as shown by the absence of significant statistical differences between the two fetus and infant groups. We observed that the features of both the lateral and the medial parabrachial nuclei are largely consistent with those reported in experimental studies. In contrast, the Kölliker-Fuse nucleus appears to be more developed in human beings than in other animal species, showing a greater extension and a more complex structure, as well as subdivision into two subnuclei (compactus and dissipatus).